The invention relates to a chips bin having a vibrating discharge with means for steaming the chips in the bin so that thorough steaming is accomplished without blockage of the chips flow. Conventionally, in the production of pulp from cellulosic fiber material, chips are fed into a chips bin, are metered from the bin into a horizontal pre-steaming vessel, and subsequently are passed to the top a continuous digestor, such as shown in U.S. Pat. No. 3,429,773. Some installations replace the horizontal pre-steaming vessel with a vertical pre-steaming vessel, such as shown in Kamyr Incorporated Bulletin No. 200C, 1968, page 23. It has been proposed to eliminate the pre-steaming vessels in such installations -- or at least minimize the size of such pre-steaming vessels -- by directly steaming the chips in the bin. However, in the past many practical difficulties have been associated with attempts to pre-steam chips in the chips bin. The volume of steam necessary to properly steam the chips in the chips bin normally results in blockage of the chips flow through the chips bin, and the difficulties in steam introduction result in a lack of uniformity in the chips treatment.
According to the apparatus of the present invention, it is possible to effect steaming of chips in a conventional vibrating discharge chips bin (called a "Vibra Bin" discharge) without blockage of chips flow, and while achieving a uniform steaming of the chips. According to the invention, even under adverse climatic conditions, where the chips are introduced into the bin in frozen condition and with ice, it is still possible to add sufficient steam to heat the entire frozen mass to above 200.degree. F. in the chips bin itself -- again without blockage of the chips flow and with completely uniform steaming of the chips.
Conventional chips bin with vibrating discharges include a generally funnel-shaped stationary top portion, and oscillatable bottom portion including a flexible material chips outlet, an activator cone connected to the bottom portion, and a gyrator for oscillating the bottom portion -- including the activator cone -- up and down with respect to the stationary top portion along a line concentric with the stationary top portion and activator cone. The activator cone is connected to the bottom portion by a plurality of arms extending radially outward from the activator. In previous, unsuccessful attempts at steaming in the chips bin, the steam has been added either underneath the activator cone, or on the side of the bin. Such attempts did not result in uniform steaming, and because of the large volume of steam that it was necessary to introduce in order to effect steaming, blockage of the chips flow often resulted.
According to the improvement of the present invention, the means for adding steam to the interior volume of the chips bin comprises a plurality of steam ports formed in each of the supporting arms of the activator cone. Each of the supporting arms has a pair of side faces disposed in generally vertical planes, and a plurality of steam ports are formed in each side face of each supporting arm. Preferably, four supporting arms are provided equally spaced around the circumference of the activator cone. Also, according to the present invention, steam is introduced underneath the activator cone, and underneath a top portion of the activator cone. In this way, it is possible to add sufficient steam to heat even frozen chips to above 200.degree.F. in the chips bin itself without affecting the flow of chips through the bin.
It is the primary object of the present invention to provide a practical system for pre-steaming chips in a chips bin. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.